Antitrust regulators have approved the $1.8 billion sale of the Carlyle Group's aviation businesses to Dubai Aerospace Enterprise Ltd., though the deal is still under review for its national security implications.

Carlyle, a leading private equity firm, said last month that it had agreed to sell Standard Aero Holdings Inc., which overhauls engines and turbines used in small jets, and Landmark Aviation, an aircraft maintenance company, to state-owned Dubai Aerospace.

The Federal Trade Commission said Thursday it completed its review of the sale of both companies and ended a waiting period for the transaction.

The sale remains under review by the Committee on Foreign Investment in the United States, a person familiar with the transaction said. CFIUS is a group of agencies chaired by the Treasury Department that reviews foreign purchases of U.S. companies for their security implications.

The transaction has not attracted the same level of scrutiny as the purchase last year of port operations at six U.S. ports by state-owned Dubai Ports World, based in the United Arab Emirates. That deal was scuttled after a firestorm of controversy in Congress.

Congressional critics of the port deal have said the sale of the Carlyle units does not present the same security risk.